In a computer network, a relay node such as a bandwidth control apparatus, a denial of service (DoS) monitoring apparatus, or an access control apparatus is utilized that performs a relay process while monitoring traffics flowing through the network. Also, in a large-scale computer network, to eliminate a bottleneck in a relay node, a load balancing technology is adopted for distributing communication data such as packets to a plurality of relay nodes by using a distribution node such as a load balancer. In this case, as bandwidth control tables (control data) for the network need to be shared among the plurality of relay nodes, a method is proposed in which one of the relay nodes is set as a master node and the master node carries out centralized management on the control data.
However, in a case where the master node carries out the centralized management on the control data, the other relay nodes functioning as slave nodes needs to transmit to the master node an update request for updating control data for relaying communication data each time the slave node relays the communication data. For this reason, traffics related to the update request flow through the network and overhead irrelevant to the original data communication may increase.